The present invention relates generally to pinion-to-gear alignment and, more particularly to, a method and apparatus for determining a pinion bearing move to achieve proper pinion-to-gear alignment based on temperature differentials of a pinion and a visual representation of a pinion-gear assembly.
Pinion-gear assemblies are widely used in a number of industrial and commercial systems, such as grinding mills. Conventional grinding mills are typically driven by a ring gear attached to the body of the mill. An electric motor or, in some circumstances, a gasoline powered engine, drives a pinion which powers the ring gear. To minimize wear and tear on the gear and pinion as well as to prevent costly down time due to broken or damaged teeth on the gear or pinion, it is imperative that the pinion be properly aligned to the ring gear. A number of techniques have been developed to properly align the pinion to the ring gear.
In one known method, an initial alignment of the pinion to the gear is achieved by collecting mechanical readings with feeler gauges and then making the best alignment possible based on those readings. Typically, this initial alignment is made with the pinion in a static condition and having no loads. As is well known, the pinion will take a slightly different position when running and under load conditions. Additionally, the alignment (or load distribution) of the pinion to the gear teeth will generate temperatures that are proportional to the load distribution. Simply, the side of the pinion with the heaviest load distribution will have higher temperatures than the side of the pinion with the lightest load distribution. These temperature differentials of the pinion when running with a load may be used to perform an alignment of the pinion-to-gear to achieve an even load distribution across the pinion teeth.
Complicating matters however, is that grinding mills are often driven by more than one pinion. Further, in grinding mills it is not uncommon for each pinion to be running in two directions. For example, autogenuous and semi-autogenuous mills are typically run in alternating directions in order to achieve longer liner life. Under these conditions, temperature data must be recorded on both pinions and in both directions. Additionally, a gear pressure angle, an angle of each pinion down from the mill center line, and a rotation of the mill while taking the temperature readings must be known in order to calculate a proper pinion move for realignment thereof. A number of computer programs have been developed to calculate pinion realignments based on temperature data. These specific programs are particularly well suited when the proper data is input directly into the program. However, it is relatively easy to make a mistake in the input of data into the computer program which ultimately could result in a damaged or broken gear or pinion due to an ill-advised alignment move. Additionally, manual calculations may be used to calculate a pinion realignment move, but manual calculations require considerable time and an extensive working knowledge of geometry as well as trigonometry.
It would therefore be desirable to design an apparatus and method for determining a pinion bearing move to align a pinion-to-gear assembly quickly and less prone to error without requiring a computer program or a number of complex manual calculations.
A method and apparatus for determining a pinion bearing move to align a pinion-to-gear assembly overcoming the aforementioned drawbacks are provided. Using a realistic visual representation of a gear to pinion mesh showing pressure angles of the gear and pinion as well as the angle of the pinion down from the mill center line allows for a quick and accurate determination of a pinion bearing move to align the pinion-to-gear. Using temperature differential data of the pinion under load conditions, the present invention allows for an easy and efficient means of determining a pinion bearing move to align the pinion-to-gear without requiring complicated manual calculations or data input to a computer program. Furthermore, the present invention is lightweight and portable thereby avoiding the drawbacks often associated with handheld electrical devices and laptop computers.
Therefore, in accordance with an aspect of the present invention, a method for determining a pinion bearing move for a pinion-to-gear alignment assembly comprises positioning a gear tooth to a first angle and positioning a pinion tooth to a starting position. The method further includes determining a pinion temperature differential, xcex94t, and repositioning the pinion tooth to a corrected position based on the pinion temperature differential. The method further includes determining a distance from the starting position to the corrected position.
In accordance with another aspect of the present invention, a nomograph includes a gear tooth having a number of temperature gradient reference marks. The nomograph further includes a pinion tooth having a pair of aligned reference lines. The nomograph further includes a gradient grid having a plurality of reference points for determining a pinion bearing adjustment move.
In accordance with yet another aspect of the present invention, a tool for realigning a pinion to gear assembly is provided. The tool includes a visual representation of a gear to pinion mesh illustrating pressure angles of a gear and pinion assembly. The tool further includes an instructional manual having a set of instructions for determining one or more pinion bearing moves based on one or more pinion temperatures.
Various other features, objects, and advantages of the present invention will be made apparent from the following detailed description and the drawings.